This guide will show you how to view previously blocked senders, and how to block new senders.
Once you have logged in (a guide on logging in can be found by clicking here), look for the Blocked section and click into it.
You will then be able to see a list of senders that are blocked. As you can see, the below sender is just an example.
You then have the option to permit or remove the blocked senders in your list. if you would like to add a new sender, click add blocked.
Enter the email address, and click add
Now click Block
You have now successfully blocked a sender!